Stornoway Diamonds owns and operates the Renard diamond mine. The mine produces very high yield and contains a high level of internal and external dilution, which can make up to 30 to 40% of the feed to the plant.

This resulted in high energy costs and tremendous wear and tear on the equipment from crushing high volumes of waste material that is not diamond bearing.

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An innovative approach was needed to address the mine’s efficiency issues, and TOMRA delivered to Stornoway Diamonds’ full satisfaction:

“You have to really envision that TOMRA has actually changed the game in terms rough diamond recovered around the world, and allowed producers to access large exceptional quality goods that perhaps in the past would be crushed to pieces,” stated Marie-Claude Hallé.

TOMRA developed the solution for Stornoway Diamonds with four key objectives for the ore sorting plant:

  • minimize diamond breakage by removing hard rocks from the crushing plant feed;
  • upgrade the quality of the material to the process plant by increasing the proportion of Kimberlite to waste rock;
  • reduce the energy required for crushing by removing the harder rocks;
  • and improve circuit efficiencies throughout the plant.

The ore sorting circuit features five TOMRA PRO Near Infrared (NIR) sorters, which are particularly well suited to enable discrimination between the various ore and waste materials based on their different chemical composition.

The plant’s large diamond recovery circuit also included a TOMRA COM XRT 2400 sorter, which uses X-Ray Transmission technology to separate material according to its specific atomic density. 

“The TOMRA solution we have in operation has offered us a very low-cost, efficient reliable means of recovering our coarse diamonds without inefficiency, without causing diamond breakage,” concluded Marie-Claude Hallé.

“It’s a very neat way to get those diamonds out of the Kimberlite at the very early stage of the process. We reduce our power consumption cost, we reduce our wear and tear on material.”